Chelsea's mid-season blip is in danger of becoming more for Enzo Maresca. His side are now four games without a win after squandering a second lead to London rivals in as many weeks. Instead of looking up the table, Chelsea are nervously checking their shoulder.

Newcastle and Manchester City have the momentum in the battle for a top four/five finish, now. The 1-1 draw to Crystal Palace promised to be a recovery and a return to form after a strong first half but ended up rearing serious issues again.

Maresca's lack of subs and game management struggles after the 60th minute continued, whilst the inverse of this problem is that he doesn't trust nearly half of a squad that has been so expensively assembled for him. The paradox at play is that, whilst Maresca has largely done well to hide a lot of the holes and troubles in his group so far, he is either now at fault for not using them more, or this is an admission that they aren't good enough.

READ MORE: Mike Dean blasts 'definite' penalty decision officials got wrong in Crystal Palace vs Chelsea

READ MORE: Pedro Neto flips at Nicolas Jackson as Chelsea discover Jadon Sancho truth vs Crystal Palace

Neither answer is particularly a good reflection for Chelsea. It will be down to Maresca, now, to try and prove both sides are wrong.

Here, football.london takes a look at the latest stories from around the club as the January window comes at an important time.

Nkunku problems

With 10 minutes left (plus added time), Maresca finally turned to his Chelsea bench against Palace. Flagging in a second half once more over the Christmas and New Year period, his change was unexpected.

Even with the narrow 1-0 scoreline, Maresca went for a change upfront. This has often seen Nicolas Jackson make way for Christopher Nkunku but this time it was for 19-year-old Marc Guiu.

Coming on for just his second-ever Premier League appearance, the £5million summer signing from Barcelona got the nod over a £52million man, a player who was one of Europe's leading attackers 18 months ago. It was a telling decision as Nkunku has been left unhappy at his position in the squad so far this season.

The Frenchman has repeatedly been left on the bench by Maresca, although he didn't take his chance away to Ipswich on Monday. Already behind Jackson in the pecking order, what did Maresca's call to bring on Guiu over him mean?

football.london says: Strip out the standing of the two players, when Guiu came on he actually made more sense as a sub. The Spaniard has more energy and presses relentlessly whenever he is on the field. Nkunku has rarely broken into a sweat.

Maybe this was a message from the head coach not only to Nkunku, but also to the board. He has flipped and flopped on his position of where Nkunku is best used, and now he has left him watching on. Looking elsewhere can be seen as a cry for more. A show of need from the men with money.

The narrative that Chelsea need a new striker won't go away after this, and neither should it. Nkunku has always been a shadow No.9 and Maresca will either have to face losing the 26-year-old or find another way to get him involved. He has fought against playing Nkunku deeper and moving Palmer elsewhere, which creates a problem.

It would be a surprise if Nkunku left this window, especially without replacement, but being second fiddle to Guiu won't be acceptable for him as an individual for long. It was a big call at Selhurst Park and it could change everything.

Centre-back swap

After his error at Ipswich Town and a wave of fresh transfer noise, Maresca's boldest call against Palace was to leave out Axel Disasi and replace him with teenager Josh Acheampong. Less than one month after the versatile full-back-cum-centre-back signed a long-term contract extension, he was handed a first league start.

Alongside fellow Cobham graduate Levi Colwill, Acheampong impressed throughout, dealing with most that Palace threw at him as well as looking composed and adventurous on the ball. For Disasi, it was telling.

Coming one day after Maresca confirmed that Wesley Fofana could be out for rest of the season, he appeared to change the hierarchy at the back with Tosin Adarabioyo also left out for Acheampong. Chelsea have been recently linked with buying another central defender.

football.london says: When Benoit Badiashile is also taken into account, Chelsea are two centre-backs down right now with Colwill the only real senior player with assured quality available. Even he is only 21.

For Acheampong, this is the start he has deserved for a while and it must now be asked just how much was lost in the three months that he was exiled throughout a contract stand-off. He could and should have been playing more, not only in the Conference League, but also domestically.

Acheampong can replace Disasi and leave Chelsea comfortable but, as has been the case all year, a new and strong, more experienced head is still needed. Fofana, who cost £70million, is an enormous loss and Disasi at £39million now seems a waste. Acheampong is the future but there's only so much of that £109million he can reasonably cover for.